Signal processing systems, such as radar and sonar systems, are useful for detecting, characterizing and monitoring various kinematic parameters associated with natural and/or man-made objects, and are important for both civilian and military operations. In radar systems, for example, one or more transmitted electromagnetic (EM) signals, referred to herein as radio frequency (RF) waveforms or pulses, are intended to engage one or more objects or targets. Reflected return signals (or echoes) are received and processed for object identification and characterization. Several types of transmitted signals may be used. For example, single pulse and multiple pulses of linear frequency modulated (LFM) waveforms may be used, with each waveform type having particular advantages in terms of target detection and velocity and acceleration estimation, by way of example only.
Surface radar systems that track targets at low elevation angles (e.g., less than 5 or 10 degrees) are adversely affected by specular multipath, or interferences which occur when a radar system receives return signals arising from discrete, coherent reflections (e.g., from surfaces such as standing water), in addition to direct line-of-sight (LOS) signals. As a result, target track metrics, such as elevation angle estimates, radar cross-section (RCS) estimates, range estimates and target sensitivity/detectability are often severely degraded at these low elevation angles. The impact of specular multipath also varies as a function of the propagation environment being operated in (e.g., standard atmosphere, evaporative ducting, sub-refractivity) as well as any surface roughness, which in many real-time applications are not know a priori. Moreover, precision track radar systems need to support multiple missions and functions simultaneously, and thus, they are often limited in available radar resources to address these problems.
Improved systems and methods for mitigating adverse track metric effects of specular multipath are desired.